So, I am driving, hear a THUMP, and it sounds like I am dragging something. Checked out the sound and it is coming from RH front wheel. I pull wheel off and nothing is stuck in wheel. I spin hub backward and there is no sound. I spin wheel forward and there is clicking noise from front differential. I spin hub backward then forward and no further noise. Drove truck for the last week, listening closely, but no noise. Has anyone else experienced this this, and do I need to be concerned? Any input would be appreciated. My truck is 2010 XLT 4x4.

 

IWEs??? partially engaged?

 

Does it sound like a paint can rattle?

Could be something with the hub (IWE) since it doesn't seem to be engaging and disengaging correctly. Otherwise, if it comes and goes, I'd be thinking something else like the check valve or solenoid that is part of the system that engages/disengages the IWE.

 

Thanks for the replies, been without a computer for a while. In the meantime, found out my truck is inadvertently trying to shift to 4x4 while I am driving. Has anyone experienced this? Is there a fix for it? Thanks in advance for replies.

 

How do you know it is trying to engage? Just by the noise it is making?

I'd still check the check valve, lines, the connector that connects the plastic lines to the rubber line that comes directly from the IWE and then the IWE's themselves. If the front system loses vacuum the IWEs will partially engage (which causes the grinding) if vacuum drop or goes completely away. Even if they fully engage because the vacuum completely disappears, you are not fully engaged in 4WD because, the transfer case isn't engaged. Reason you don't get the grinding when actually switching to 4wd on the move is because the system will spin up the half shafts via the front diff and transfer case to match the speed the wheels are spinning at and then it will engage the IWEs by dropping vacuum.

 

I found out because the EIC showed "four wheel shift in progress" as I was driving.

 

Okay, then there is something else going on that is trying to engage them. When you switch it, the system spins up the half shafts to match the speed that you are going if you happen to be moving at the time. If all it is doing when it is switching is just engaging the IWE that would definitely cause your grinding. This is definitely a new symptom I have not read about or seen.

Maybe try pulling the cable off the battery and doing a complete reset of the system by leaving it unplugged for at least 30 minutes. Maybe a reboot of the system will work. Guess on my part.

 

I will try that.

 

My first thought is that something is wrong with the switch. If it was a vacuum problem (which is way too common), you wouldn't get the computer message.